1. Field of the invention
The present invention relates to an image forming apparatus which includes exposure units each disposed opposite to a corresponding photoconductor.
2. Description of related art
Among image forming apparatuses for forming an image on a recording sheet, the so-called tandem type image forming apparatus is known in the art (e.g., see patent documents 1-3 listed below) which typically includes exposure units arranged in tandem and each disposed above and opposite to a corresponding photoconductor. The exposure units may be LED heads, for example, which use light-emitting diodes (LEDs) as a light source for forming an electrostatic latent image on a photoconductor. Varieties of such image forming apparatus known in the art include, for example: type I (as disclosed in patent document 1) in which a frame on which cartridges each containing a photoconductor are supported is slid upward to render any of the cartridges replaceable; and type II (as disclosed in patent documents 2 and 3) in which cartridges each containing a photoconductor or a frame on which the cartridges are supported can be pulled out horizontally for replacement of the cartridges.
<Cited Reference Documents>
Patent document 1: JP 2003-43776 A (see FIG. 3); corresponding U.S. patent issued under U.S. Pat. No. 6,708,011 B2
Patent document 2: JP 8-36346 A (see FIG. 3)
Patent document 3: JP 2006-98772 A (see FIG. 13); corresponding U.S. patent application published under US 2006/067734 A1
In the conventional image forming apparatuses, each exposure unit (LED unit) is disposed above and opposite to the corresponding photoconductor, and thus special consideration in designing the apparatus used to be given to a path along which each cartridge is removed from or attached to the apparatus, particularly in view of the operation carried out when a cartridge containing a photoconductor is replaced. For example, the path is so designed as to avoid a space being occupied by the exposure unit; alternatively, each exposure unit is configured to be moved away from the path (from above the corresponding cartridge) every time when the cartridge is replaced. This would presumably be detrimental to the convenience of operation.
It would thus be desirable to provide an image forming apparatus having an exposure unit disposed opposite to a photoconductor, in which the operability in replacement of a cartridge containing a photoconductor is improved. The present invention has been made in an attempt to eliminate the above disadvantages. Illustrative, non-limiting embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an illustrative, non-limiting embodiment of the present invention may not overcome any of the problems described above.